chore: clear the mechanical lint and type findings

Dead imports and locals removed, each blocks keyed, `any` narrowed to unknown.
Two context setters kept their calls and lost only the unused binding; the
settings redirect no longer awaits a parent whose data it discards. A leading
underscore now marks a binding that only holds a position.

frontend/src/routes/(root)/(library)/+layout.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
 	import BookDelete from '$lib/components/forms/book-delete.svelte';
 	import { BookEdit } from '$lib/components/forms/edit-book';
-	import { getBookOperationsState, setBookOperationsState } from '$lib/state/bookOperations.svelte';
+	import { getBookOperationsState } from '$lib/state/bookOperations.svelte';
 	import { getLibraryState } from '$lib/state/library.svelte';
 	import { setBookSelectionState } from '$lib/state/bookSelection.svelte';
 	import type { Snippet } from 'svelte';

frontend/src/routes/(root)/(library)/book/[bookId]/+page.svelte

@@ -28,22 +28,16 @@
 	import { getBookOperationsState } from '$lib/state/bookOperations.svelte.js';
 	import { getBookshelfState } from '$lib/state/bookshelf.svelte.js';
 	import { getLibraryState } from '$lib/state/library.svelte.js';
-	import { Progress } from '$lib/components/ui/progress/index.js';
 	import * as Accordion from '$lib/components/ui/accordion/index.js';
 	import * as Table from '$lib/components/ui/table/index.js';
 	import * as AlertDialog from '$lib/components/ui/alert-dialog/index.js';
 	import ShelfCreateDialog from '$lib/components/forms/shelf-create-dialog.svelte';
-	import { untrack } from 'svelte';
 
 	let { data } = $props();
 
-	// Seeded once, then kept in sync by the effect below — untrack says so
-	// explicitly rather than capturing the initial value and warning about it.
-	let book = $state(untrack(() => data.book));
-
-	$effect(() => {
-		book = data.book;
-	});
+	// Follows the loaded book, and stays assignable so an edit can update it locally
+	// until the next navigation supplies a fresh one.
+	let book = $derived(data.book);
 
 	const bookOps = getBookOperationsState();
 	const libraryState = getLibraryState();

frontend/src/routes/(root)/+layout.svelte

@@ -1,9 +1,7 @@
 <script lang="ts">
-	import { listBookshelves } from '$lib/api';
 	import AppSidebar from '$lib/components/layout/app-sidebar.svelte';
 	import SiteHeader from '$lib/components/layout/site-header.svelte';
 	import UploadTray from '$lib/components/layout/upload-tray.svelte';
-	import { Loading } from '$lib/components/ui/command';
 	import * as Sidebar from '$lib/components/ui/sidebar/index.js';
 	import type { Library, PaginatedResponse } from '$lib/schema';
 	import { setBookOperationsState } from '$lib/state/bookOperations.svelte';
@@ -28,8 +26,8 @@
 	// init. `untrack` says that explicitly, instead of silently capturing the
 	// initial value and warning about it.
 	const libraryState = setLibraryState(untrack(() => data.libraries.items));
-	const bookshelfState = setBookshelfState();
-	const bookOps = setBookOperationsState(libraryState.activeLibrary!.id);
+	setBookshelfState();
+	setBookOperationsState(libraryState.activeLibrary!.id);
 	const theme = setThemeState(untrack(() => data.theme));
 
 	// Set here rather than beside the upload dialog so a running import survives

frontend/src/routes/(root)/settings/+layout.svelte

@@ -41,7 +41,7 @@
 		     of libraries; the row above it is overflow-hidden, so without this a
 		     long list is clipped rather than reachable. -->
 		<nav class="flex w-48 shrink-0 flex-col gap-1 overflow-y-auto">
-			{#each items as item}
+			{#each items as item (item.routeId)}
 				<a
 					href={resolve(item.routeId)}
 					class="rounded-md px-3 py-2 text-sm font-medium transition-colors hover:bg-muted {page

frontend/src/routes/(root)/settings/+page.ts

@@ -1,8 +1,6 @@
 import { redirect } from '@sveltejs/kit';
 
-export async function load({ parent }) {
-	const { libraries } = await parent();
-
+export async function load() {
 	// Immediately redirect to the account settings
 	redirect(303, `/settings/account`);
 }

frontend/src/routes/(root)/settings/devices/+page.svelte

@@ -130,7 +130,7 @@
 					</Table.Row>
 				</Table.Header>
 				<Table.Body>
-					{#each data.devices as device}
+					{#each data.devices as device (device.id)}
 						{@const isVisible = visibleApiKeys.has(String(device.id))}
 						<Table.Row class="h-14">
 							<Table.Cell class="pl-4 font-medium">

frontend/src/routes/(root)/settings/libraries/+page.svelte

@@ -31,7 +31,7 @@
 				</Table.Row>
 			</Table.Header>
 			<Table.Body>
-				{#each libraryState.libraries as library}
+				{#each libraryState.libraries as library (library.id)}
 					<Table.Row class="h-14">
 						<Table.Cell class="w-16 pl-4 text-center text-lg font-semibold"
 							>{library.name[0]}</Table.Cell

frontend/src/routes/api/[...path]/+server.ts

@@ -137,7 +137,7 @@ export const DELETE: RequestHandler = async ({ params, locals, fetch, request, u
 		const headers = prepareRequest(locals, request);
 
 		// DELETE may or may not have a body
-		let options: RequestInit = {
+		const options: RequestInit = {
 			method: 'DELETE',
 			headers
 		};

frontend/src/routes/login/+page.svelte

@@ -1,9 +1,7 @@
 <script lang="ts">
-	import { replaceState } from '$app/navigation';
 	import LoginForm from '$lib/components/forms/login-form.svelte';
 	import SignupForm from '$lib/components/forms/signup-form.svelte';
 	import * as Tabs from '$lib/components/ui/tabs/index.js';
-	import { redirect } from '@sveltejs/kit';
 
 	let tabValue = $state('login');
 </script>